Helicopter



Aug. 8, 1933.-

F. BORDONI' HELICOPTER 4 Sheet-Sheet 1 Filed Feb. 26, 1932 FERDINANDOBORDONI INVENTOR ATTORNEYS 3- v I F'..BORDONI 4 ,805

HELICOPTER I 1 Filed Feb. 26, 1952 A SheetsI-Sheet 3 FERDINA NDO BORDONI mvsnrog a ATTQIYQ'SI '1 Aug. 8, 1933.

F. BORDONI HELICOPTER Filed Feb. 26, 1952 4 Sheets-Sheet 4 FERDINANDOBORDONI INVENTOR miudi ATTORNEYS reamed Au 3, 1933 "UNITED STATES PATENToFFica HELICOPTER Ferdinando Bordoni, Rome, Italy Application February26, 1932, Serial No. 595,282,- and in Italy February 17, 1931 10 Claimsof the pilot, so as to maintain unaltered or to vary at will the liftingpower of the propeller,

'both in amount and in direction, and also in order to give rise to atorque lying in a plane normal to the axis of rotation, which may bevaried at will both as to amount and direction of rotation.

-verse direction when the angle of incidence actions, or by takingadvantage of the moment of the said aerodynamic reactions with respectto the longitudinal axis of rotationmf each blade,

or also by utilizingthe variations of the axial thrust-of thepropellers. 3

In all these cases, it is preferable that the blades should possess asmall moment of inertia with respect to the longitudinal axis ofrotation (and consequently a considerable elongation),

and it is necessary also to construct the blades with such a profilethat the resultant centre of the thrust of the aerodynamic reactions maynot be shifted, or only slightly shifted in the transthe blade isvaried.

When the blades satisfy the above mentioned conditions, it iseasy toprovide for their control It thus P i l t cause he pparatustofbyffollowingwither therfirst, the second or the rise or to fall, orto shift it in the horizontal or an oblique direction, or to incline itin the longitudinal or in the transversal directions, (and also allowthe correction of the eventual list) and it is also possible to causethe apparatus to rotate in the horizontal plane. so as to guide it inthe direction desired, and also to veer it in any desired manner.

The said mechanism also makes it possible to,

on the fundamental principle consisting in that,-

if to a propellers blade which is hinged to the hub,- the angle ofincidence is varied periodically during one revolution (which would havethe effect of varying periodically the relative aerodynamical thrust)the said blade performs oscillations, which, combining with the'rotarymovement will have the effect of changing the plane of rotation of theblade, and consequently also of the direction of the'lifting thrust.

with regard to the automatic control of the amount of the liftingthrust, the said mechanism can be actuated in three different ways, vizby utilizing,. forthe automatic control, the inclination which theblades assume under the actionof the centrifugal force and theaerodynamic rethird methods above mentioned, as will appear more clearlyfrom the following detailed description, and with reference to theannexed drawings,

which illustrate schematically a helicopter made,

according to the present invention considered as a whole, and includesthe construction and 8 Figs. 3 and 4 show respectively in vertical axialsection and in plan elevation one way of articulating the blades to thehub.

Figs. 5, 6, 7 and 8 show various sections blades.

Figs. 9 and 10 show schematically'two diiferent forms of construction ofthe device for the control of the blades.

Figs. 11 and 12 show schematically two diflerent arrangements forconnecting the motor to the propellers.

Figs. 13 and 14 illustrate in perspective and in detail, respectively,of-the controlling means by which to tip and adJust the propeller bladeadjusting rings. 4 a.

As may be seen in Fig. 1, which shows the helicopter in complete form,including a body 1 in which are arranged the places a for thepassengers, and in front of these, the seat 3 for the pilot; the motor 4being disposed behind.

The body or hull is provided with elastic means 5 and 6 for landing,which, as shown in the draw-' ings, may take the form of skids. Nowheels are required 'as the apparatus. has 'no need to run of the wheelsmay be provided in order to facilitate the shifting of the apparatus onthe ground.

The apparatus may also be arranged to rise from or descend upon thewater, in which case 5 suitable floats may be provided.

The body is also provided with fixed tail Sta-- bilizing surfaces 7 and8, the object of which is to improve the stability of flight during thehorizontal movement of the apparatus; whereby the horizontal plane 7 caneventually be made to oscillate and to be controllable so as to provideto the centering of the apparatus, and to the variations of thelongitudinal trim during the horizontal travel of the apparatus. 0

Also the vertical plane 8 may eventually be controlled, soas to be ofassistance in turning.

In addition, the body may also be provided with small wings which proveto be useful during These devices comprise two propellers 10 at? 11,co-axial with each other, rotating in opposite directions and driven bythe motor 4.

of the star type cooled by air by means of the fan 12 mounted on themain shaft 13 of the motor; it is however possible to use other types ofmotors and other systems of cooling.

by a fan, it is necessary to convey and direct the air currentaccurately on the radiating ribs of the cylinders 14, by guiding thefiuid streams by means"of metal plates 15 suitably shaped (as shownschematically in Fig.2) so as to obtain the desired result with theleast possible consumption of power. p

Fig. 2 shows the case in which a motor is fitted obliquely, so that theshaft 13 transmits the movement directly to the first propeller 10 bymeans of a speed reducing gearing formed by the pinion 16 and thetoothed wheel 1'7.

The propeller 10 is provided with a hollow hub 18 revolving on the fixedtube 19 acting as a bear- 50. ing, and transmits the movement to thesecond propeller 11, which is also mounted on a hollow hub 20, saidtransmission comprising the two toothed wheels 21 and 22 and the pinions23.

It is also possible to adopt' other means for transmitting the movement,such alternative means being shown by way of example in the Figures 11and 12.

In the arrangement shown in Fig. 11, the shaft 13 of the motor 4 drivesthe vertical shaft 56 by means of a pair of conical wheels 55 (which canbe omitted when the motor is placed with the vertical axis below thepropellers), the said vertical shaft being provided, in correspondencewith each propeller,. with a pinion 57 which engages with one, two,three or more pinions 58 mounted causes therotation of .the firstpropeller through the pinion 84, the satellite pinions and the toothedcrown 66 connected to the said propeller,

- and it also causes the-rotation, m the opposite In Fig. 2 is shown byway of example, a motor When using a motor cooled by air suppliedtransversally tothe blade) direction, of the second propeller, by meansof another pinion 6'7, and other satellite pinions'68, (the cage ofwhich is connected to the second propeller) and of a toothed fixed crown69.

In order to allow the free rotation of the pro- 8 pellers, even when themotor is cut off or clogged, and in order to be able thus to descendwhen the propellers rotate freelyby taking advantage of their action asparachute, it is necessary to introduce between the motor and thepropellers a dis- 3 connecting device or a free wheel arrangement 24which is schematically shown in Fig. 2.

The propellers may be provided with a variable number of blades, forexample 2, 3, or 4, which may have any suitable. shape; these blades are9 attached to the hub by means of hinges 25, 26, 2'7 and 28 which allowthem to set themselves in thedirection of the resultant of thecentrifugal force and of the axial thrust; in this way the bendingmoment on the blades is eliminated or 9 at least greatly reduced.

The said blades are in addition free to rotate round a longitudinal axiswhich is approximately parallel to the leading ed'geJQegause they mustbe able to changetheir angle of -incident:e wit'ITT G respect to therelative wind.

' Itisaisaadvantageous to allow the blades to oscillate slightly intheir plane of rotation, so as to eliminate or reduce the alternatemovements 10 which developtiiflhat plamdhfllare caused by the combinedeffect of the rotation me ings of the blades, or by thecombin'ed effectof the rotation of the blades and the movements of the apparatus.

It may however be preferable and more con- 11* venient from anaerodyna'mical point of view to use stops (eventually of the elastictype) inserted in .the hinges. This causes naturally theproductionmLhiwstrains in the blades when they are at rest,wmeweyenlmasily 11 maintained within practical limits by allottirig theblades convenient dimensions.

Moreover the propellers, according to the present invention, are alsoprovided with a control mechanism of the blades, which allows thevariation of the angle of incidence, either automatically or under thecontrol of the pilot, so as to maintain unaltered or to change at willthe lifting power of the machine, both in amount and in direction, asbefore stated, and also to change at will 121 the resisting torque ofthe propeller; the said actions being required to produce the vertical,oblique and horizontal movements of the apparatus, and to cause it toveer in any direction re,- quired'. The said control mechanism mayassume 131 many different forms, by varying the shape, the arrangementand the working of the parts composing it, while obtaining the sameresult.

Amongst the various possible forms of construction, some are describedhereinafter by way of example. I

A first form is shown in Figs. 3, 4, 5, 6, 'l and 8, in which the blades29 and 30 are free'to revolve and to oscillate by means of the thrustbearings 31 and 32, and'of the'radial bushes 33 and 34. In 141 the formshown by these figures it'is supposed to do away with the third hingewhich allows the blades to oscillate inthe plan of rotation.

The bushes 33 and 34 are fixed on the hubs 35 and as which rotate roundthe tube 19 by 141 means of the bushes 31 and 38.

The longitudinal axis-oi rotation of each blade is arranged to passthrough the centre of thrust of the blade (which-iasabove said doesnotshift I The blades are moreover constructed and counterweighted sothat their centre of gravity also placed on the axis of rotation.

In the conditions above described, whichever be the arrangement or theincidence of the blades,

40, which are connected to the two rings 43 and 44 by means of the links41 and 42.

Supposing in the first place that the said two rings are invariablymounted on the hubs 35 and 36, the automatic-control of the blades actsin the following way.

If for example an axial wind begins to blow, which has the tendency ofincreasing or decreasing the angle of incidence of the blades, thesewill be solicited to rise or fall, in order to reestablish theequilibrium between the centrifugal and the axial forces; however, asthe links 4l and 42 are fixed (Figs. 4 and 5) and are also connected tothe blades eccentrically with. respect to the longitudinal axis ofrotation, they force the blades to rotate round said axis thus bringingback the incidence of the blades to approximately the original value. Itwill now be evident that the mechanism above described operates in sucha way as k to maintain almost unaltered the moment of the axial thrustacting on each blade, for a given velocity of rotation of the propeller,and as the contain within small limits the variations of thethrust, orat least, asv it is found by the mathematical treatment of the problem,they cause to vanish the first harmonic of the variable thrust.

in the conditions of flight above. described it is thus apparent, asbefore mentioned, that it is convenient that the blades should possess asmall moment of inertia, so as to allow them to perform their necessarycontinuous angular oscillations with very small torsional momentums.

If on the other hand the rings 43 and 44 are not fastened to thehubsfbut by means of two rows of balls, are simply connected with thesleeves 45 and 46 which do not revolve with the propellers but aresubjected to axial and angular movements controlled by the pilot, itbecomes thus possible to vary at will the conditions of flight. In'other words, if the said sleeves are lifted or lowered simultaneously,the conditions of equilibrium of the blades will be varied, and

consequently also the resultant axial thrust,

plane.

-movement to the rings 70 and "71 by means of Finally if the sleeves 45and 46 are shifted angularly either in the longitudinal or in thetransverse directions, it will be apparent that the said arrangementwill causetheperiodical variation of the angle of incidence of theblades at each revolution, which fact, as already mentioned at thebeginning of this description, will cause the blades to'oscillate, andwill also change the position of the plane of rotation of the twopropellers, which will be forced to rotate in planes parallel to eachother and obliquely with respect to the tube 19; the resultant thrustswill be shifted and they will'become inclined, giving rise to momentswithrespect to the centre of gravity of the apparatus, and will causethis latter to incline in the longitudinal or transversal plane. Inparticular, if the apparatus is inclined forward and is maintained .insuch position, the lifting thrust acquires an horizontal component whichcauses a movement of translation.

With regard to the control of the sleeves 45 and 46, Figs. 3 and 4 showthat each sleeve is controlled with three rods 47 (and 48) disposed intothe tube 19. 1

It is also possible to cause the rods 47 and 48 to descend outside thetube 19 (when this is used as the shaft for the rotation of the blades,as shown in Figs. 11,' and 12) providing of course this tube withsuitable expansions in correspondence with the propellers, so' that therods 48 may be carried without hindrance through the central part of thepropeller 10.

Of course, the control of the rods 47 and 48 may be effected in manydifferent ways; one of which consistingin connecting the said rods todiscs or rings which by suitable transmission may be controlled by thepilot either axially or angularly (said transmissions may also be madeto reach directly the sleeves 45 and 46).

Fig. 13 particularly illustrates the connection of the rods 47 and 48 tothe slidable rings 70 and 71, respectively, said rings, as alreadyindicated, being subjected to axial and angular movements.

In order to render such movements feasible, the

rings are mounted on the spherical joints 72 and 73, which latter inturn are fixed upon telescopic tubes '74 and 75, respectively, thesetubes being adapted to slide axially the rod 76 secured to the housing77.

Ihe mentioned slidable rings may be controlled by the pilot by means ofappropriate transmission devices, such as for example, a control lever78, a foot lever '79, and a lifting lever 80. If the control lever '78which is mounted on a spherical pivot 82 and is therefore shiftable inall directions, should be shifted forwards. .or backwards by the pilotin the direction indicated by the arrow 81, he can impart angular therods 83, thus producing the angular movement of the rings 45 and 46,through the connecting rods 47 and 48: This angular movement in turnproduces the alternate and periodical oscillations of the blades roundtheir longitudinal axes, which, owing to the aerodynamical reactionsalready described, produce the inclination of. the rotating planes ofthe propeller and -lar shifting of the rings 70 and'll in a plane 0 ofthe rods 4'7 and 48.

which is normal to the plane in which the said rings would oscillatewhen moved by the rods 83, the said angular shifting being similarlytransmitted to the rings 45 and 46 by means The resultant of saidmovement is a transversal inclination of the rotating planes of thepropellers and consequently the variation of the transversal trim of theaircraft.

When the pilot with his foot depresses the end of the lever 79 which ispivoted at 91, he will cause this lever to oscillate in a horizontalplane, this oscillation, by means of the transmission formed by the rods92, the two bent levers 94, pivoted at 95, and the small connecting rods96, will cause the axial sliding in opposite directions of thetelescopic tubes 74 and 75. As a consequence there will occur a shiftingof the rings thrusts on the blades increase or decrease, also 70 and 71which are fixed on the said tubes, which latter are subjected tooppositely directed axial movements, so that while the rods 47 arelifted, the rods 48 are lowered, these movements being followedrespectively by the collars 45 and 46, so that the angles of attack ofthe two propellers, as already described, are modified, the

' resulting dissymmetry of the horizontal couples 1 of reaction causingthe apparatus to rotate in the horizontal plane.

Fig. 14 shows the compensating spring 51 adapted to counteract the liftthrust of the blades, and the means for controlling it. This spring willbe deformed more or less according to the stresses transmitted to it bythe rods 47 and 48, thus causing the movements of the casing 77' andconsequently, also movements of the rods 4'7 and 48, for ensuring, asalready stated, the automatic control of the sustaining thrust.

In order to set the apparatus into a rising or falling condition, itwill be necessary to adjust the compression of the spring 51 so as tochange the equilibrium trim at will, and in order to accomplish this itwill be sufficient to operate the lifting control 80, which is connectedto the spring 51 by means of the connecting rods 9'7 and 99 and thelever 98, instead of said control being directlyconnected to the box 77by means of the same connecting rods as shown in Fig. 13. i

To the members above described, it will be sufiicient to add the motorhandle, or this may be provided with an automatic regulator formaintaining an even speed of rotation of the propellers even when theload varies; or else the pilot may have at its command a handleforchanging the positionof equilibrium of the said regulator andconsequently for controlling the speed of the propellers.

A second form of construction can be attained by applying the second ofthe arrangements above mentioned for the control of theblades.

If the longitudinal axis of rotation of the blades is placed a littleforward with respect to the centre of thrust of the aerodynamicreactions (viz, between the leading edge and the said centre of thrust)and the blades themselves are counterweighted so that the centre ofgravity lies instead on the axis of rotation (or in any case be nearerto this axis than the centre of pressure) every blade will be constantlyaffected by a yawing moment which, supposing the centre of thrust to befixed, results in becoming proportional to the said pressure.

Assuming that the mechanism of control of the blades is similar to thatshown in the Figures 3, 4, 5, 6, 7 and 8, having however the bushes 31,32, 33 and 34 so close to the axis that the extensions 39 and 40 have avery small length, the oscillations of the blades will not produce inthis case any perceptible variations in the incidence of the saidblades, but the yawing moment of the blades will be transmitted to therods 47 and 48 through the links 41 and 42 and the sleeves 45 and 46.

If therefore (Fig. 9) the, said rods 47 and 48, after traversing acontrol box 49, engage upon a flat disc 50, which is free to moveaxially, on this disc there will be developed a force which will beproportional to the sum of the yawing moments of the blades, viz.proportional to the sum of the lift thrust of the blades, which forcecan be equilibrated or counteracted by means of a spring 51, or by otherequivalent means, based for example on the centrifugal force developed.

If therefore, because of the axial wind the by the rods 47 and 48 on thedisc 50 will become greater or smaller than the reaction exerted by thespring 51; the disc 50 will consequently be shifted and the blades willrevolve until the thrust is re-established. g

Of course, by adjusting the compression ofthe spring, the conditions ofequilibrium can be altered as required and consequently the apparatusrises or falls, shifting then, by means of the control box 49, the rods47 in a direction opposite to the rods 48. Thus it is possible todistribute the driving couples between the propellers, and consequentlythe whole apparatus can be made to rotate. Furthermore, by shifting therods 47 and 48 through unequal amounts (always by means of the controlbox 49) it is possible to incline angularly the sleeves 45 and 46, andconsequently the planes of rotation of the propellers and the directionof the lifting force can'be set obliquely.

Finally it is also possible to operate the control of the blades by athird method "which is based on the utilization of the variations of theaxial thrust.

If the tube 19 (Fig. 10) supporting the propellers is connected to thebody or hull of the apparatus not rigidly but through an elastic system52 (comprising for example a si'nglespring and a pile of rings mountedconcentrically with respect to the tube 19 and enclosed within a tube 53fixed to the body) to any variation of the resultant lift thrust, therewill be a corresponding axial movement of the tube 19, caused by theyielding of the elastic system.

Supposing now that the blades are controlled by the above described linkrods 41 and 42, attached at one end very close to the hinges of theblades themselves and the other end to the rings 43 and 44, controlledby the sleeves 45 and 46 and by the rods 47 and 48.

If the rods-47 and 48 are fixed to the body 53, as every variation ofthe lift thrust produces, as stated before, a shifting of the tube 19, arelative movement is thus produced which alters the angle of incidenceof the blades, and this is suflicient to restore the equilibrium, in thesame way as described in the second form of construction.

When, on the other hand, the rods 47 and 48 are'not rigidly fixed to thebody, but are led to a control box 54, fixed on the body, similar to thebox shown in Fig; 9,.it is possible to perform all the operations thatmay be desired; in particular, when the rods 47 and 48 shiftingtogether, the inclination of all the blades is changed simultawhen itsstate of compression or tension is varied,

the equilibrium becomes restored for a slightly different value of theaxial thrust, and by continuing the manual operations, the desiredvariation of thrust can be attained.

In the system now described it is of course necessary that the tube 19be attached to the body so as to be free to slide but not to rotate, sothat it may also transmit the torsion moments which are obtained bydisplacing the rods 47 in the contrary direction to the rods 48.

' Itis moreover necessary that in the transmission between the motor andthe propellers, a shaft of the telescopic type or even of the cardanjointed type (if obliquely disposed), is inserted, so as to ensure thetransmission of power in spite of the relative displacements occuringbetween the propellers and the body, unless it is preferred to connectthe motor rigidly to the system of the propellers and to elasticallyconnect the whole apparatus to the machine body.

I claim: 1. A helicopter provided with a shaft and fitted with twocoaxial propellers revolving in opposite directions and having bladeswhich are provided with an articulation allowing the blades to oscillatein a plane passing through the center of said shaft and automaticallyadjust themselves in the direction of the resultant of the centrifugalforce combined with the aerodynamical thrust, which propeller blades arerotatable about their longitu dinal axes, and oneach propeller areconnected to I a ring vwhich is individual to the propeller andindividually movable relatively to the propeller shaft in order toproduce variations of the angle of incidence of the blades, whereby tovary the value of the lifting thrust, and means for moving each of saidrings, which latter, in'uneven or dissimilar setting, cause theformation of a differential couple for veering the machine as a whole,and in even or similar setting, cause a periodic variation of the angleof incidence of the blades so as to oscillate the latter and therebyproduce inclination of the plane of rotation of the propellers and varythe direction of the lifting thrust thereof, there being means forrotating said propellers.

2. A helicopter according to claim 1, having automatic means for movingthe rings pertaining to the propellers.

3. A helicopter according to claim 1, having controlled means for movingthe rings pertaining to the propellers.

' 4. A helicopter according to claim 1, having link rods connecting theblades of the propellers with movable rings controlling the angle ofincidence. of said blades, which produce the rota-' tion of the-bladesabout their longitudinal axes by the eflectof the variations of thelight thrust,

and as 'a result produces the automatic variation of theang le ofincidence in the proper direction for maintaining the axial thrust ofthe apparatus practically constant. T

5. A helicopter according to claim 1, wherein Y the centre of thrust ofthe propeller blades is disposed outside their longitudinal axes ofrotation, a disk associated with the helicopter capable of assumingsolely axial displacements, axially sliding control against said diskand communicating stresses and strains thereto tending to displace thesame, and regulatable means simultaneous exerting an opposing force onsaid disk, so that axial sliding of the rods and automatic control ofthe propellers is produced by the resultant force exerted on the disk,there being,

other control "devices for obtaining other movements of the helicopter.1

6. A helicopter according to claim 1, and thrust bearings controllingthe rings which regulate the angle of incidence of the propeller blades,together with two groups of control rods disposed along the shaft of thepropellers, there being control devices for operating and moving saidcontrol rods.

'7, A helicopter accordingto claim 1, provided with a tube carrying thepropellers, means elastically suspending the body of the machine to saidtube in order to actuate the automatic control of the rings duringflight, and means cooperating therewith for increasing or decreasingtheaxial thrust in order to vary the length and thereby produce concordantrotation of theblades about their longitudinal axes, there being"additional means for further controlling the operation of the machine.

8. A helicopter according to claim 1, wherein the body of the machinecarries the means for. rotating the propellers in the form of a motorhaving a shaft, the propeller shaft being common to both propellerswhich are rotatable about the same while one propeller is mounted abovethe other, a hollow hub on the lower propeller provided with a gearthereon, a pinion on the motor shaft meshing with said gear to directlydrive said lower propeller, a hollow hub on the upper propeller alsohaving a gear thereon, and means including additional gearingcommunicating ro- I tation to said latter gear and the upper propellerfrom the gear of the lower propeller and driving ing a crown gear,'themeans for driving the propellersconsisting of a motor having a shaft,and the propeller shaft being rotatable within the propeller hubs, andmeans communicating rotation from the motor shaft to the propellersincluding gears rigid; on said propeller shaft meshshaft which isvertically disposed and driven by 5 said motor shaft, a pinionconnecting the motor shaft with said vertical propeller shaft, whichpropeller shaft communicates its rotation to one propeller by-means of apinion, one or more satel- 1'25 ing with pinions on one end of rotaryspindles lite pinions and acrown gear engaging'wit'h said one propeller,and similarly communicates its rotation to the other propeller by meansof anotherpinion, asecond group of satellite pinions mounted in a casingwhich is connected to said other propeller, and a flxed crown gear.

\ FERDINANDO BORDONL-

